FIGURE 5.

Cotranscriptional folding of the E. coli leader RNA of the tRNA^phe synthetase operon for two different transcription speeds. For slow transcription (top) the completely transcribed chain shows a nearly zero density for the terminator structure (solid black line), and transcription of the full-length operon proceeds. For fast transcription, most of the fully elongated molecules form the terminator structure (dashed line). Thermodynamic equilibrium is reached only on very long (>10¹⁰) time scales.